External
In addition to the above points, it is important to be aware of the statute of limitations applying in each state (obtained through the local law society office).
While not directly impacting on the decision to write off an overpayment, being aware of statute parameters will ensure that overpayments are not left written off for excessive periods of time.
By commencing recovery action before statute parameters are reached, any potential for the debtor to seek waiver in a court of law will be alleviated.